linux-kernel - [PATCH 2/2] dmaengine: qcom_hidma: pause the channel on shutdown

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Date:   Sat, 25 Mar 2017 19:04:03 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     dmaengine@...r.kernel.org, timur@...eaurora.org
Cc:     linux-arm-msm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Sinan Kaya <okaya@...eaurora.org>,
        Andy Gross <andy.gross@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Vinod Koul <vinod.koul@...el.com>, linux-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] dmaengine: qcom_hidma: pause the channel on shutdown

We need to ensure that all DMAs and interrupts are cleared during
shutdown operation in order for kexec to start the next kernel clearly.

Otherwise, HW could be performing a DMA into random addresses in the
middle of second kernel start.

Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
---
 drivers/dma/qcom/hidma.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c
index 3c982c9..5072a7d 100644
--- a/drivers/dma/qcom/hidma.c
+++ b/drivers/dma/qcom/hidma.c
@@ -865,6 +865,20 @@ static int hidma_probe(struct platform_device *pdev)
 	return rc;
 }
 
+static void hidma_shutdown(struct platform_device *pdev)
+{
+	struct hidma_dev *dmadev = platform_get_drvdata(pdev);
+
+	dev_info(dmadev->ddev.dev, "HI-DMA engine shutdown\n");
+
+	pm_runtime_get_sync(dmadev->ddev.dev);
+	if (hidma_ll_disable(dmadev->lldev))
+		dev_warn(dmadev->ddev.dev, "channel did not stop\n");
+	pm_runtime_mark_last_busy(dmadev->ddev.dev);
+	pm_runtime_put_autosuspend(dmadev->ddev.dev);
+
+}
+
 static int hidma_remove(struct platform_device *pdev)
 {
 	struct hidma_dev *dmadev = platform_get_drvdata(pdev);
@@ -908,6 +922,7 @@ static int hidma_remove(struct platform_device *pdev)
 static struct platform_driver hidma_driver = {
 	.probe = hidma_probe,
 	.remove = hidma_remove,
+	.shutdown = hidma_shutdown,
 	.driver = {
 		   .name = "hidma",
 		   .of_match_table = hidma_match,
-- 
1.9.1